Dynamic Modelling of a Spar Buoy Wind Turbine

2017 ◽  
Author(s):  
Giuseppe Roberto Tomasicchio ◽  
Alberto Maria Avossa ◽  
Luigia Riefolo ◽  
Francesco Ricciardelli ◽  
Elena Musci ◽  
...  
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Dynamic Modelling ◽  
Irregular Waves ◽  
Induced Response ◽  
Simulation Tool ◽  
Floating Structure ◽  
Mooring Lines ◽  
Wave Basin ◽  
Fast Wind

In the present paper, the dynamic response of a spar buoy wind turbine under different wind and wave conditions is discussed. Physical model tests were performed at the Danish Hydraulic Institute (DHI) off-shore wave basin within the EU-Hydralab IV Integrated Infrastructure Initiative. The OC3-Hywind spar buoy was taken as reference prototype. A spar buoy model, 1:40 Froude-scaled, was tested using long crested regular and irregular waves, orthogonal (0 degrees) and oblique (20 degrees) to the structure. Here the results concerning regular waves, with incidence orthogonal to the structure, are presented; the selected tests considered rotating and non-rotating blades. Measurements of displacements, rotations, accelerations, forces response of the floating structure and at the mooring lines were carried out. Based on the observed data, FAST wind turbine simulation tool, developed and maintained by the U.S. Department of Energy’s (DOE’s), National Renewable Energy Laboratory (NREL), was calibrated and verified. The numerical model takes into account the wave induced response and the effects of the mooring lines on the overall system. The adopted spar buoy has three equally spaced mooring lines that were modelled as quasi-static taut or catenary lines through MAP++ (static module) and MoorDyn (dynamic module) in the FAST simulation tool. The tensions along the fairleads of the three mooring lines were examined. At the end of the calibration procedure, the numerical model was successfully used to simulate the dynamic motions of the floating wind turbine under combinations of wind and sea states for the selected wave attacks. All data from the DHI tests were converted to full scale using Froude scaling before being analyzed.

scholarly journals Numerical Analysis of a Catenary Mooring System Attached by Clump Masses for Improving the Wave-Resistance Ability of a Spar Buoy-Type Floating Offshore Wind Turbine

2019 ◽  
Vol 9 (6) ◽  
pp. 1075 ◽  
Author(s):  
Zhenqing Liu ◽  
Yuangang Tu ◽  
Wei Wang ◽  
Guowei Qian
Keyword(s):  
Wind Turbine ◽  
International Energy Agency ◽  
Wave Resistance ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Induced Response ◽  
Mooring Lines ◽  
Energy Agency

The International Energy Agency (IEA), under the auspices of their Offshore Code Comparison Collaboration (OC3) initiative, has completed high-level design OC-3 Hywind system. In this system the wind turbine is supported by a spar buoy platform, showing good wave-resistance performance. However, there are still large values in the motion of surge degree of freedom (DOF). Addition of clump masses on the mooring lines is an effective way of reducing the surge motion. However, the optimization of the locations where the clump masses are added is still not clear. In this study, therefore, an in-house developed code is verified by comparing the results of the original OC3 model with those by FAST. The improvement of the performance of this modified platform as a function of the location of the clump masses has been examined under three regular waves and three irregular waves. In the findings of these examination, it was apparent that attaching clump masses with only one-tenth of the mass of the total mooring-line effectively reduces the wave-induced response. Moreover, there is an obvious improvement as the depth of the location where the clump masses mounted is increased.

Experimental Investigation vs Numerical Simulation of the Dynamic Response of a Moored Floating Structure to Waves

2014 ◽  
Author(s):  
Daniele Dessi ◽  
Sara Siniscalchi Minna
Keyword(s):  
Dynamical Behavior ◽  
Irregular Waves ◽  
Mooring Line ◽  
Floating Structure ◽  
Mooring Lines ◽  
Wave Energy Converters ◽  
Time Histories ◽  
Actual Configuration ◽  
Proper Orthogonal ◽  
Dynamic Wave

A combined numerical/theoretical investigation of a moored floating structure response to incoming waves is presented. The floating structure consists of three bodies, equipped with fenders, joined by elastic cables. The system is also moored to the seabed with eight mooring lines. This corresponds to an actual configuration of a floating structure used as a multipurpose platform for hosting wind-turbines, aquaculture farms or wave-energy converters. The dynamic wave response is investigated with numerical simulations in regular and irregular waves, showing a good agreement with experiments in terms of time histories of pitch, heave and surge motions as well as of the mooring line forces. To highlight the dynamical behavior of this complex configuration, the proper orthogonal decomposition is used for extracting the principal modes by which the moored structure oscillates in waves giving further insights about the way waves excites the structure.

scholarly journals Proposal and Performance Study of a Novel Mooring System with Six Mooring Lines for Spar-Type Offshore Wind Turbines

2021 ◽  
Vol 11 (24) ◽  
pp. 11665
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chao Wang ◽  
Yuangang Tu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Offshore Wind Turbine ◽  
Mooring System ◽  
Mooring Lines ◽  
Included Angle ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

Spar-type floating offshore wind turbines commonly vibrate excessively when under the coupling impact of wind and wave. The wind turbine vibration can be controlled by developing its mooring system. Thus, this study proposes a novel mooring system for the spar-type floating offshore wind turbine. The proposed mooring system has six mooring lines, which are divided into three groups, with two mooring lines in the same group being connected to the same fairlead. Subsequently, the effects of the included angle between the two mooring lines on the mooring-system’s performance are investigated. Then, these six mooring lines are connected to six independent fairleads for comparison. FAST is utilized to calculate wind turbine dynamic response. Wind turbine surge, pitch, and yaw movements are presented and analyzed in time and frequency domains to quantitatively evaluate the performances of the proposed mooring systems. Compared with the mooring system with six fairleads, the mooring system with three fairleads performed better. When the included angle was 40°, surge, pitch, and yaw movement amplitudes of the wind turbine reduced by 39.51%, 6.8%, and 12.34%, respectively, when under regular waves; they reduced by 56.08%, 25.00%, and 47.5%, respectively, when under irregular waves. Thus, the mooring system with three fairleads and 40° included angle is recommended.

Dynamic Response of Spar-Type Floating Offshore Wind Turbine in Freak Wave

2019 ◽  
Author(s):  
Yougang Tang ◽  
Yan Li ◽  
Peng Xie ◽  
Xiaoqi Qu ◽  
Bin Wang
Keyword(s):  
Dynamic Response ◽  
Wind Turbine ◽  
Offshore Wind ◽  
Modulation Method ◽  
Power Coefficient ◽  
Offshore Wind Turbine ◽  
Floating Structure ◽  
Mooring Lines ◽  
Freak Wave ◽  
Floating Offshore Wind Turbine

Abstract Simulations are conducted in time domain to investigate the dynamic response of a SPAR-type floating offshore wind turbine under the scenarios with freak wave. Towards this end, a coupled aero-hydro numerical model is developed. The methodology includes a blade-element-momentum model for aerodynamics, a nonlinear model for hydrodynamics, a nonlinear restoring model of SPAR buoy, and a nonlinear algorithm for mooring cables. The OC3 Hywind SPAR-type FOWT is chosen as an example to study the dynamic response under the freak conditions, while the time series of freak wave is generated by the Random Frequency Components Selection Phase Modulation Method. The motions of platform, the tensions in the mooring lines and the power generation performance are documented in different cases. According to the simulations, it shows that the power coefficient of wind turbine decreased rapidly at the moment when freak wave acted on the floating structure.

Global Analysis of a Floating Wind Turbine Using an Aero-Hydro-Elastic Numerical Model: Part 2—Benchmark Study

2011 ◽  
Author(s):  
Neil Luxcey ◽  
Harald Ormberg ◽  
Elizabeth Passano
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Global Analysis ◽  
Weather Conditions ◽  
Irregular Waves ◽  
Benchmark Study ◽  
Floating Wind Turbine ◽  
Calm Water ◽  
Internal Forces ◽  
System Power

This paper describes and presents the results of a benchmark study of a floating wind turbine numerical model that includes aero- and hydro-elasticity. The modelled wind turbine is the NREL offshore 5 MW baseline wind turbine whose specifications are publicly available. The first part of this paper demonstrates the importance of including aeroelasticity and hydroelasticity in the system. Power production, internal forces and motion amplitudes are compared to results from models using a rigid tower and rigid blades. Comparisons are performed for different weather conditions such as calm water, regular and irregular waves, constant and varying wind. The consequences of including elasticity in the different parts of the model are studied. The second part of the paper presents a benchmark study against the codes of the Offshore Code Comparison Collaboration. The floater motions, blade and tower deflection and power generation are presented and discussed.

scholarly journals Proposal of a Novel Mooring System Using Three-Bifurcated Mooring Lines for Spar-Type Off-Shore Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8303
Author(s):  
Shi Liu ◽  
Yi Yang ◽  
Chengyuan Wang ◽  
Yuangang Tu ◽  
Zhenqing Liu
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Line Length ◽  
Torsional Stiffness ◽  
Irregular Waves ◽  
Mooring Line ◽  
Mooring System ◽  
The Novel ◽  
Mooring Lines ◽  
Floating Wind Turbine

Floating wind turbine vibration controlling becomes more and more important with the increase in wind turbine size. Thus, a novel three-bifurcated mooring system is proposed for Spar-type floating wind turbines. Compared with the original mooring system using three mooring lines, three-bifurcated sub-mooring-lines are added into the novel mooring system. Specifically, each three-bifurcated sub-mooring-line is first connected to a Spar-type platform using three fairleads, then it is connected to the anchor using the main mooring line. Six fairleads are involved in the proposed mooring system, theoretically resulting in larger overturning and torsional stiffness. For further improvement, a clump mass is attached onto the main mooring lines of the proposed mooring system. The wind turbine surge, pitch, and yaw movements under regular and irregular waves are calculated to quantitatively examine the mooring system performances. A recommended configuration for the proposed mooring system is presented: the three-bifurcated sub-mooring-line and main mooring line lengths should be (0.0166, 0.0111, 0.0166) and 0.9723 times the total mooring line length in the traditional mooring system. The proposed mooring system can at most reduce the wind turbine surge movement 37.15% and 54.5% when under regular and irregular waves, respectively, and can at most reduce the yaw movement 30.1% and 40% when under regular and irregular waves, respectively.

Effect of Nacelle Drag on the Performance of a Floating Wind Turbine Platform

2019 ◽  
Author(s):  
Daewoong Son ◽  
Pauline Louazel ◽  
Bingbin Yu
Keyword(s):  
Wind Turbine ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Simulation Tool ◽  
Floating Structure ◽  
Drag Forces ◽  
Floating Wind Turbine

Abstract Wind forces acting on an offshore wind turbine are transferred to the bottom of the tower and consequently to the floating structure. Thus, drag forces acting on each component of the wind turbine such as the blades, the nacelle, and the tower must be accounted for properly in order to evaluate the performance of the supporting platform. In the aero-elastic wind turbine simulation tool FAST v.7, the nacelle drag component, however, has not been implemented, which means that only the drag forces on the tower and on the blades are represented. In this work, the front and side nacelle drag forces are modelled in FAST v.7 via different drag contributions. This paper will examine the behavior of a floating offshore semisubmersible platform, the WindFloat, for different Rotor-Nacelle-Assembly (RNA) yaw-misalignments with emphasis on the nacelle drag component.

Experimental Validation for Motion of a SPAR-Type Floating Offshore Wind Turbine Using 1/22.5 Scale Model

2009 ◽  
Author(s):  
Tomoaki Utsunomiya ◽  
Tomoki Sato ◽  
Hidekazu Matsukuma ◽  
Kiyokazu Yago
Keyword(s):  
Wind Turbine ◽  
Simulation Method ◽  
Offshore Wind ◽  
Irregular Waves ◽  
Scale Model ◽  
Offshore Wind Turbine ◽  
Floating Offshore Wind Turbine ◽  
Wave Basin ◽  
Tank Experiment ◽  
Made In

In this paper, motion of a SPAR-type floating offshore wind turbine (FOWT) subjected to wave loadings is examined. The proposed prototype FOWT mounts a 2MW wind turbine of down-wind type, whose rotor diameter is 80m and hub-height 55m. The SPAR-type floating foundation measures 60m in draft, having circular sections whose diameter is 12m at the lower part, 8.4m at the middle (main) part and 4.8m at the upper part. The FOWT is to be moored by a conventional anchor-chain system. In order to design such a FOWT system, it is essential to predict the motion of the FOWT subjected to environmental loadings such as irregular waves, turbulent winds, currents, etc. In this paper, the motion of the FOWT subjected to regular and irregular waves is examined together with the application of steady horizontal force corresponding to steady wind. The wave-tank experiment is made in the deep sea wave-basin at NMRI (National Maritime Research Institute), using a 1/22.5 scale model of the prototype FOWT. The experimental results are compared with the numerical simulation results for validation of the simulation method.

scholarly journals Numerical Study of a Moored Structure in Moving Broken Ice Driven by Current and Wave

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Biao Su ◽  
Karl Gunnar Aarsæther ◽  
David Kristiansen
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Torsional Stiffness ◽  
Coupled Analysis ◽  
Mooring Line ◽  
Floating Structure ◽  
Mooring Lines ◽  
Broken Ice ◽  
Ice Field ◽  
Drifting Ice

This paper presents a numerical model intended to simulate the mooring force and the dynamic response of a moored structure in drifting ice. The mooring lines were explicitly modeled by using a generic cable model with a set of constraint equations providing desired structural properties such as the axial, bending, and torsional stiffness. The six degrees-of-freedom (DOF) rigid body motions of the structure were simulated by considering its interactions with the mooring lines and the drifting ice. In this simulation, a fragmented ice field of broken ice pieces could be considered under the effects of current and wave. The ice–ice and ice–structure interaction forces were calculated based on a viscoelastic-plastic rheological model. The hydrodynamic forces acting on the floating structure, mooring line, and drifting ice were simplified and calculated appropriately. The present study, in general, demonstrates the potential of developing an integrated numerical model for the coupled analysis of a moored structure in a broken ice field with current and wave.

Wave reflection effects on small craft motions

1996 ◽  
Vol 23 (2) ◽  
pp. 340-346
Author(s):  
Michael Isaacson ◽  
John Baldwin ◽  
Andrew Kennedy
Keyword(s):  
Numerical Model ◽  
Wave Reflection ◽  
Numerical Study ◽  
Diffraction Theory ◽  
Coastal Engineering ◽  
Irregular Waves ◽  
Induced Response ◽  
Small Craft ◽  
Wave Heights ◽  
Wave Induced

This paper describes an experimental and a numerical study of the wave-induced response of a moored vessel near a reflecting wall, for the purpose of incorporating wave reflection effects into wave agitation criteria for small craft harbours. The motions of a model vessel have been measured for a range of wave heights, wave periods, wave directions, mooring conditions, and vessel locations, and with both regular and irregular waves. These have been compared with the results of a numerical model based on linear diffraction theory. An expression is developed to relate vessel motions near a partially reflecting wall to motions in unreflected waves. This has been found to agree well with the experimental results, and is used to recommend an extension to existing wave agitation criteria for small craft harbours so as to take account of the presence of reflecting walls. Key words: coastal engineering, harbours, hydrodynamics, marinas, wave agitation, waves.

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